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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 236-241 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Commercial cellulase preparations from Trichoderma viride and Aspergillus niger were immobilized on porous silica glass and ceramics such as alumina and titania with titanium tetrachloride (TiCl4) and on their silanized derivatives with glutaraldehyde (GLUT). The amounts of the immobilized enzymes were in the range 10-50 mg/g carrier (dry) depending on the kind of carrier and immobilization method. Their activities toward carboxymethyl cellulose (CMC), xylan, aryl-β-glucoside, and aryl-β-xyloside were 3-53% of those of the native enzymes. The optimum pH of the enzymes shifted to the acidic side in most cases, whereas the optimum temperatures were nearly the same as those of native ones. The activity of immobilized enzyme preparations towards CMC did not change significantly during continuous operation over a periods of 60 days. Finally, xylan was hydrolyzed with the immobilized enzymes, and the sugars formed were investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 41-53 
    ISSN: 0006-3592
    Keywords: baculovirus ; insect cell ; p97 ; glycosylation ; GPI anchor ; protein expression ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The baculovirus/insect cell system (Autographa californica multiple nuclear polyhedrosis virus/Spodoptera frugiperda Sf9 cells) was used to express the GPI-anchored human melanoma tumor antigen, melanotransferrin or p97. This system served to study the expression and productivity of recombinant GPI-anchored p97 by insect cells. The Sf9 cells expressed a cell surface GPI-anchored form of p97 as well as a soluble form of p97 that did not appear to be derived from the GPI-anchored form of p97. Both recombinant forms, although Endo H resistant, migrated slightly faster (∼88 kDa) than the native p97 (∼95-97 kDa). The insect GPI-anchored p97 was sensitive to PI-PLC, which exposed a detectable cross-reacting determinant. The Sf9 cell surface p97 expression was similar to that of human melanoma (SK-MEL-28) cells, whereas the Sf9 cell specific secretion rate was 10-fold higher. Also Sf9 cells retained considerably higher levels of p97 within the cell. The Sf9 cell surface expression of p97 varied with time after infection, with the maximum expression, which appeared independent of multiplicities of infection greater than 1, occurring at 48 h. After 48 h, levels of cell surface and secreted p97 fell whereas p97 retained within the cell increased, which possibly reflected the lytic nature of the expression system. The successful expression of GPI-anchored human p97 by the baculovirus/insect cell system not only provides a source of p97 for further research but also is the basis of an alternative method for the commercial production of GPI-anchored proteins. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 41-53, 1997.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 14 (1989), S. 619-622 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The incorporation and amphoteric behavior of Si impurities in Si-doped (100) oriented molecular beam epitaxial (MBE) GaAs layers grown under different As4/Ga flux ratios but with a fixed Si flux have been studied using Hall effect measurements, photothermal ionization spectroscopy and photoluminescence. The Si donor concentration increases substantially with increasing As4/Ga flux ratio, while the Si acceptor concentration remains less than ∼ 1013 cm-3, regardless of the variation of As4/Ga flux ratio. The observed increase of carrier concentration with increasing V/III ratio is not due to a change of site preference of Si impurities from Ga to As sublattice sites as previously supposed, but is due to the increase in incorporation of Si donor. This result can be explained by the kinetic effects associated with surface reaction processes involved in Si impurity incorporation. From these results it is clear that the sticking coefficient of Si is less than unity, and varies with the growth conditions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 892-898 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The mechanism of oxidation of copper at the alloy/film interface, and the subsequent migration of copper ions in barrier-type films, has been examined for anodizing of an Al - 1.5 wt.% Cu alloy with a prior chemical polishing treatment. Both chemical polishing and anodizing result in formation of a thin layer of alloy at the alloy/film interface, of ∼2 nm thick, that is highly enriched in copper. The layer is present immediately beneath the different types of film formed by chemical polishing and subsequent anodizing, and contains in both cases ∼6 × 1019 Cu atoms m-2. The amount of copper contained within the enriched layer of alloy is not significantly dependent upon the anodizing voltage. During anodic film growth, both aluminium and copper ions are incorporated into the film at the alloy/film interface, on average in their alloy proportions. However, the film is depleted in copper relative to the alloy because copper ions in the film migrate faster than Al3+ ions and, on reaching the film/electrolyte interface, are ejected directly to solution. The mechanism of oxidation of copper is proposed to depend upon the formation, through prior oxidation of aluminium, of copper-rich clusters in the enriched layer of alloy at the alloy/film interface. Individual clusters are oxidized only on achieving a critical size. Consequently, copper is incorporated into the film discontinuously both in time and in position along the alloy/film interface. The films contain a high population density of flaws, which affects the film composition, the uniformity of ionic current, the faradaic efficiency of film growth, and the detailed distributions of copper ions within the films. However, the general features of film growth are compatible with the usual growth mechanism of anodic alumina, with transport numbers of Al3+ and O2-/OH- ions of ∼0.4 and ∼0.6, respectively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 525 (1985), S. 230-236 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Verbindungsbildung im System PbGeO3—Pb5Ge3O11Die Verbindungsbildung im System PbGeO3—Pb5Ge3O11 wurde mittels Thermoanalyse und Hochtemperatur-Röntgenbeugung untersucht. Neue Modifikationen des PbGeO3 und Pb5Ge3O11 wurden durch gleichzeitige Hydrolyse von Blei- und Germanium-alkoxiden dargestellt. PbGeO3 hat eine hexagonale Einheitszelle mit a = 15,573 und c = 7,240 Å und Pb5Ge3O11 besitzt eine orthorhombische Kristallstruktur mit a = 5,081, b = 7,301 und c = 8,817 Å. Sie werden in die bekannten monoklinen und hexagonalen Modifikationen bei 575 bis 610°C bzw. 410 bis 450°C umgewandelt. Eine Verbindung der Zusammensetzung Pb3Ge2O7 wird nicht bestätigt. Die Strukturen der Germanatgruppen in den Bleigermanaten werden auf der Grundlage von IR-Daten diskutiert.
    Notes: Compound formation in the system PbGeO3—Pb5Ge3O11 was studied by thermal analysis and high-temperature X-ray diffraction. New modifications of PbGeO3 and Pb5Ge3O11 were prepared by the simultaneous hydrolysis of lead and germanium alkoxides, followed by washing and drying; the former has a hexagonal unit cell with a = 15.573 Å and c = 7.240 Å, and the latter has an orthorhombic crystal structure with a = 5.081 Å, b = 7.301 Å and c = 8.817 Å. They are transformed to the known monoclinic and hexagonal modifications at 575 to 610°C and 410 to 450°C, respectively. No compound of Pb3Ge2O7 was confirmed. The structures of germanate groups in the lead germanate compounds are discussed on the basis of the infrared spectral data.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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